The invention relates generally to methods and apparatuses for isolating nucleic acids.
Nucleic acids have a variety of usages in different areas such as detection or diagnosis area. Detection or diagnosis at the nucleic acid level is more sensitive or specific than at, e.g., the protein level. Analytes such as crude extracts from tissues like plant or animal tissue, cell lysate, or blood or urine samples comprise, besides nucleic acids, other species (or impurities) at least some of which may inhibit the nucleic acid detections or masking the detection results, so it is usually necessary to isolate nucleic acids from the impurities. Analytes comprising nucleic acids are usually available in small amounts, so amplification techniques like the polymerase chain reaction (PCR) or reverse-transcriptase-polymerase chain reaction (RT-PCR) are developed. Sometimes, one of requirements to isolation of nucleic acids would be obtaining amounts of nucleic acids from analytes enough to be used in the subsequent amplification procedures.
Different technologies have been developed to isolate/separate/purify nucleic acids. For example, U.S. patent application publication No. 2005/0112658 discloses a method of isolating and purifying a nucleic acid under a centrifugal force, U.S. patent application publication No. 2007/0221563 discloses a method for separating and purifying a nucleic acid under pressure, and international patent application publication No. 2007/104962 directs to a method for separating nucleic acids from a liquid sample by allowing the liquid sample to flow along a bibulous membrane so that the nucleic acid is distributed along the length of the membrane.
It is disclosed, e.g., in U.S. Pat. No. 7,067,287 that quartz filter paper may be used as the solid phase bondable to nucleic acids in methods for the recovery of nucleic acids under centrifugal forces or pressures and including particles. However, it is not found yet that quartz fiber filters are actually used in isolating/separating/purifying nucleic acids possibly it is not suitable for use in particle format and it is more well known for use in air sampling which is much different from isolating/separating/purifying nucleic acids. Another reason the quartz fiber filter is not been actually used in isolating/separating/purifying nucleic acids may be it is believed to be too dense to sorb nucleic acids.
Centrifugal force and pressure need instruments to generate the force and pressure and specific operation skills, and are thus undesirable, e.g., for places where expensive instruments and skilled persons are not affordable. In addition, centrifugal force and pressure may break down chains of nucleic acids into too short strings, resulting in that only nucleic acids of relatively small size could be obtained. Separating by distribution along the membrane may sometimes have concerns in qualities because both of nucleic acids and impurities together are spread out on the membrane.
Therefore, there is a need to develop a new method and apparatus for isolating nucleic acids.